Zero speed indicating devices and processes for testing same

ABSTRACT

The subject invention is directed to methods, processes and decisions on test outcomes for testing for faulty, therefor dangerous, performance of zero speed indicators that are used to control the opening of barriers guarding moving machine components. The indicators may be tested by removing them from the components during operation without shutting down production or in certain situations the indicators may be tested during the run down phase of the components caused by machine stop initiations. The tests allow to anticipate and hence prevent hazardous opening of barriers due to a faulty zero speed indication. Additionally, the invention is directed to testing of the insertion of motion interference devices in conjunction with zero speed indicators, both of which must perform correctly in order to permit the unlocking and opening of the protective barrier. There are included various exemplary devices for effecting the testing function.

This application is a divisional application carved out of currentlypending application Ser. No. 10/054,249 filed Nov. 13, 2001 andentitled: Zero Speed Indicating Devices and Process for Testing Same,which is a divisional application of Ser. No. 09/165,717 filed Oct. 2,1998 that issued as U.S. Pat. No. 6,389,875.

THE FIELD OF THE INVENTION

This invention relates to the testing for faulty, therefore dangerous,performance of various types of zero speed indicators that are used toprevent a machine guard from being opened until the machine has come toa complete stop or has slowed sufficiently to prevent injury to anyoneintending to access or work on the machine in the guarded space. Thetesting methods, devices, processes and decisions on test outcomes, areconstructed and arranged so that the indicators can be tested while themachine is running, preventing unnecessary production interruptions andmachine shutdowns, as well as take advantage of scheduled andunscheduled machine shutdowns to perform the tests. By performing thesetests the hazardous opening of a guard due to a faulty zero speedindication can thus be anticipated and prevented.

For additional safety, machine guard protective systems will sometimesutilize motion interference or blocking devices which are inserted inthe motion path of a component of the stopped machine so that machinemotion cannot take place while the guard is open. The present inventionfurther relates to the testing of the insertion of motion interferenceor blocking devices in conjunction with zero speed indicators, both ofwhich must perform correctly in order to permit the unlocking andopening of the guard.

BACKGROUND OF THE INVENTION

Barrier guards, shields, covers, screens and the like are among theoldest known safeguards for protecting personnel from the hazards ofmoving machinery. Their effectiveness derives from three properties:they prevent entry of the body into the zone of operation, they retainexpelled missiles, and they define the safe from the unsafe portions ofthe machine. The need to access machinery leads to the removal oropenings of barriers whereupon their concomitant protection is lost.Heretofore the shortcomings have been addressed by interlocks, whichprovide a connection between a barrier and the control or power systemof the machinery to which the barrier is fitted. The interlock and thebarrier with which it operates is designed, installed and adjusted sothat until the barrier guard is closed into its protective state theinterlock prevents the machinery from operating by interrupting thepower medium, and also so that opening of the barrier causes the hazardto be eliminated before access is possible or it may be necessary thatthe barrier remain closed and locked until the risk of injury from thehazard has passed.

The barrier locking system wherein the barrier is to remain locked untilthe risk of injury from the hazard has passed is necessary wheneither 1) simply opening or removing the guard does not eliminate thehazard before access is possible or 2) opening a guard other than atpredetermined points in the machine cycle may expose the hazard.

The guard locking system will normally consist of a timing device ormotion or position sensing device and a guard locking device. These maybe individual units or combined in one assembly. Variable conditions ofoperation of machinery produce variable amounts of run down and in thesecircumstances a timing device may be inappropriate to determine when therun down has reached a non-hazardous state since it has to be set forthe longest run down time that might be expected. The variable timeelement may, however, be eliminated by the use of a motion or positionsensing device, which allows the guard to be opened as soon as thehazard is no longer present.

Available on the market today are a number of position, motion, timingand guard locking devices that operate on various principles. Amongmotion and position sensing devices some may suffer from thedisadvantage that they show poor response at low speed and are thereforeacceptable only where residual motion after the guard has been openedcould not cause injury. On the other hand, where injury could resultfrom residual motion, more sensitive devices and or timing devices maybe necessary. Examples of typical motion or position sensing devices area) rotation sensing devices that may operate on centrifugal force,friction, eddy current generation, voltage generation, optical orelectronic pulse generation b) photo-electric beam c) proximity devicesor d) position switches or valves.

Timing device examples include a) mechanical, electrical or electronicclocks b) delay relays c) sequence valves d) threaded bolt or e) adashpot.

Examples of typical guard locking devices are a) a captive-key unit b) atrapped-key unit c) mechanical bolt or d) shotbolts which may besolenoid operated, hydraulic or pneumatic.

The present invention relates to the testing of motion sensing devicesthat indicate zero speed or the cessation of motion. These devicesactively monitor moving machine elements and are never benign when themachine is active. Such indicating devices may wear out or get out ofadjustment or otherwise fail by prematurely signaling that motion hasbeen arrested. This leads to unlatching of the barrier guards before themotion has ceased and before entry to the protected regions is safe. Astatistically significant number of people will depend on the efficacyof the motion detectors to unlock guards when it may not be safe to doso.

To help prevent a false sense of security, it is desirable to improvethe reliability of motion detectors and reliance thereon by regularlytesting them. The dependence on zero speed systems is entirely analogousto the public's reliance on the “safety edges” on ordinary elevatordoors.

Zero speed indicators may be completely removed from machines and testedby methods specified by the manufacturers. This procedure is practicalonly when infrequent inspections are anticipated and when the safety ofthe basic machine is not compromised by the removal of the motionindicator such as during a general machine shutdown.

The present invention describes a process whereby the motion detectorsare frequently and automatically tested in situ while the machinery isin motion (and production) and while total personnel protection isassured. A further novel process is envisioned where the motiondetectors are automatically tested in situ whenever the machine is shutdown, such as when control systems stop switches are activated for lunchbreaks, routine cleaning, maintenance or end-of-shift, when emergencystop devices are employed, when power disconnect is effected; or whenlatchless interlocked barriers are opened. In addition, when the motiondetector indicates that the moving parts have stopped, it may be desiredthat absolute safety be insured by requiring a motion blocking member tobe insertable and inserted between the now stopped moving parts before aguard protecting such parts can be opened.

SUMMARY OF THE INVENTION

There are many applications of safety closures or barriers that mustremain closed and locked until the dangerous components that are guardedcome to a stop. In such situations it is usual to employ run downcompletion detection devices such as motion detectors, zero speedswitches indicators or detectors, timing devices, delay devices,interference devices, and motion blockers to make a final check todetermine that the machine has in fact come to the required stop.

The present invention is directed to the testing of zero speedindicators and the incorporation of interference or motion blockingdevices into the overall testing process of guard closures whether suchclosures are used separately from or in conjunction with interlocks,closure locks, zero speed indicators, and various testing devices. Thetesting, methods of testing, testing process, testing systems anddevices for interlocks, guard closures and closure locks have beenextensively detailed in two patent applications filed in the names ofthe two inventors of the present invention. These applications areincorporated by reference into the present application and set forth indetail the testing, methods of testing, testing processes testingsystems and devices for interlocks, guard closures and closure locks.One application has Ser. No. 08/861,328, filed on May 21, 1997, entitledREMOTE AND PROXIMAL INTERLOCK TESTING MECHANISM AND TESTING SYSTEMS. Theother application has Ser. No. 09/033, 322 and was filed on Mar. 2, 1998and is entitled REMOTE AND PROXIMAL GUARD TESTING SYSTEMS AND TESTINGSYSTEMS EITHER SEPARATELY OR IN CONJUNCTION WITH INTERLOCK TESTINGMECHANISMS AND SYSTEMS.

By way of reference, the above patent applications disclose the methodsand means for testing in situ of guard interlocks, guard closures, andclosure locks on machines, without stopping the machine or interruptingproduction to perform the tests, and the detection by the test of afault in any of them does not lead to stopping of the machine unless sodesired. If the machine is permitted to continue to run after thetesting detects a fault or faults, remedial actions can be instituted topostpone repairs of the failures to a future convenient time. Theinterlocks are tested to determine whether any of them have failed,hence will not perform, as they should when called upon to execute theirintended safeguarding functions. The guard closures are tested todetermine whether any of them can be opened when they should be closedand locked to alert against a false sense of security that entry intothe hazardous spaces they are meant to protect is prevented when it isnot. The failure to prevent the guard closure from opening can be due tovarious causes. One of these can be the failure of its lock to keep theguard closure “shut” disclosing both a closure failure and a lockfailure. Closure locks are also tested by direct means.

A zero speed indicator essentially consists of a device that will detectand indicate when the machine component speed it is measuring has cometo the required stop, i.e., either has been reduced to zero or whereapplicable to a value sufficiently close to zero determined to benon-hazardous to personnel contact. In the present invention, unlessotherwise indicated the term zero speed and its variants, means therequired stop as defined above, and zero speed detectors are also zerospeed indicators with both terms used synonymously. Furthermore, any onezero speed indicator may serve more than one guard closure protectedspace. Therefore, statements referring to one zero speed indicator and aguard closure and/or closure lock served by it, should be understood asreferring to all guard closures and/or their locks served by the zerospeed indicator.

The zero speed indicators are in some manner attached to the moving partof the machine being guarded and will be indicating the movement of themachine, and thus if they reflect a zero speed reading the guard may beopened. However, to open the guard with impunity it is essential thatthe zero speed indicators be periodically tested to make sure that whenone relies on its indication of zero speed that in fact the machine hascome to the required stop.

Normally, a zero speed indicator is attached to or driven by anycomponent of a moving machine whose speed is proportional to the speedof the hazardous elements that require protection by guard closures. Asthe motion of the monitored component decreases to zero, the zero speedindicator has an opportunity to detect and signal the achievement of therequired stop motion which, in turn, becomes a permissive or necessarycondition for unlatching the guard closure.

The present invention includes a first novel process for testing theaccuracy and reliability of the zero speed indicator while the machinecomponent is running under power. In this process the zero speedindicator is temporarily uncoupled in situ, i.e., isolated from themonitored component by removing it or by declutching it from thecomponent or by any other suitable means. Without the driving impetusfrom the machine component, the zero speed indicator will eventually rundown to the required stop motion. If desired, the zero speed indicatormay be decelerated by braking devices to save time. If the zero speedindicator is a device without integral speed rundown components, e.g. aphotoelectric device, then such a zero speed indicator will have to beprovided with a speed rundown component as part of the test setup. Inthe isolated state any known suitable testing methods or devices may beused to verify the accuracy of the zero speed indicators. If the zerospeed indicator fails to operate properly, the guard closure lock shouldremain latched for the sake of safety until a repair has been completed.It may also be desirable to actuate “test failed” warning indicators anddevices, and in some circumstances, it may be desirable to shut themachine down while maintaining the interlock function and unlatching theguard closures so that maintenance may proceed unencumbered.

In accordance with the present invention the first novel processprovides for testing the motion indicators in situ for accuracy andreliability, while the protected machine components are running underpower. If the test determines that a motion indicator of a guardprotected space will fail to indicate correctly the occurrence of a safestop, it provides the great advantage of detecting this in advance ofallowing a prospective opening of the guard and gives early warning ofthis prospective safety failure. With such warning available, steps canbe instituted and devices provided to maintain the protective guardlocked, preventing a future entry into the hazardous space until ascheduled repair or replacement of the faulty motion indicator takesplace. In contrast, the reliance on the motion indicator's correctperformance without testing it in advance fosters a false sense ofsecurity, and leads to the concomitant hazard of prematurely allowing aprospective entry into the guard protected space. With the preventivesteps in place, the entry protection of the guarded space is secured,and the machine need not be stopped nor production disrupted upondetecting the motion indicator's failure. Likewise, the machine can bestopped and allowed to be safely restarted as long as the access to thehazardous space continues to be barred. Repair and replacement of thefailed motion indicator can be scheduled for whatever time isappropriate. The aforementioned novel process is designed to provide allof these novel advantages otherwise absent without it.

It should be noted that the novel motion detector verification testmethod or device used in the proposed process is not equivalent to azero speed indicator system with a redundant motion indicator.Regardless of the level of redundancy, without the novel process of thepresent invention, failure of a motion detecting system can not bedetermined while the machinery is in powered operation. Consequently,advanced warning of such failure and the deployment of associatedcounter measures will not be possible.

In accordance with the present invention there is also provided a secondnovel process for testing zero speed indicators without interrupting theoperation or production capability of the machine and without the needto uncouple the zero speed indicator from the monitored component.

This novel process applies to machines that operate with intermittentdangerous motions. Their zero speed detectors can readily be testedduring the motion run down phase when the intrinsic or natural movementsin the points or zones of operation are caused to come to rest asrequired by the machine operation process. An example may be found inthe power press operating in the “single stroke” mode where its staterepeatedly moves between clutching and declutching and braking.

In this regard it is important to note that every moving machine elementhas a “speed run down” phase when required to stop. Therefore, theoperation of zero speed indicators during intermittent stops areintrinsically no different than during any other machine stops.

Specifically, continuously operating machinery that are monitored bymotion detectors achieve a state of rest whenever control stops areinitiated or when emergency stops are executed or when lockoutprocedures call for power interruption. In such instances, analogous tothe intermittent motion machines, it is possible to test the zero speedindicators during the machine's run down to the state of rest withoutinterrupting production or uncoupling of the zero speed indicators fromthe monitored components.

In the above referred to applications for testing zero speed indicatorswhen machine stops are initiated a variety of known suitable testingmethods or devices may be used to verify the accuracy of the zero speedindicators during the machine run down phase, including those employedfor such verification testing in the first novel invention processpreviously described. Failure of the zero speed indicating systemdetected by the verification test will preclude the unlatching of thelock or locks of the guard closure or closures it serves. Only afterrepairs or replacements have restored the reliability of the motiondetector to correctly indicate zero speed will it be trusted to givepermission to unlatch the locks. With their guard locks latched, theaffected hazardous spaces remain protected, denying entry to personnel.Hence the machine can be restarted and production can continue in spiteof the presence of a known faulty motion detector. Furthermore, therepairs or replacements of the faulty motion detector can now bescheduled for what ever time is suitable.

Thus, the aforementioned second novel process provides for testing ofthe motion indicators in situ for accuracy and reliability, and thetesting to be done while the protected machine components are in the“running down” phase of a stop initiation. This provides the advantageof being able to detect if a motion detector will fail to indicatecorrectly when the safe stop of the running down phase will occur, andto warn thereof in advance of a prospective opening of the guard. Havingsuch warning available, steps can be instituted and devices provided tomaintain the protective guard locked when such failure is detected,preventing entry into the hazardous space until a scheduled repair orreplacement takes place, or until assurance is gained by other meansthat a safe stop is present. In contrast, the reliance on the motiondetector's correct performance without testing it fosters a false senseof security, and leads to the concomitant hazard of prematurely allowingentry into a guard protected space. With the preventive steps in place,the entry protection of the guarded space is secured and the machine canbe stopped and allowed to be safely restarted to continue production aslong as the access to the hazardous space continues to be barred.Repairs and replacements of the failed motion indicator can be scheduledfor whatever time is appropriate. This novel process is designed toprovide all of these novel advantages otherwise absent without it.

A third novel aspect of the present invention is associated with theinsertion of blocking devices into the points or zones of operation orinto synchronized power trains that will absolutely prohibit dangerousmachine motions.

Interlocked and locked guard closures with zero speed monitoringcapability are intended to protect personnel from hazardous movingmechanical elements regardless of whether the motion is attributable toexternal power sources or internal stored energy. Access to theoperational zones protected by guard closures is granted only afterhazardous motion has subsided. As a final step in operator protection,this invention anticipates situations where an interference system willbe deployed in synchronized power transmission trains or into the zoneof operation that will prevent all movement before a guard closure lockunlatches and allows the operators to place their bodies into the hazardzone. Die blocks and props are typical interference devices used inzones of operations. Application of the interference system must bepreceded by the establishment of zero motion by a zero speed detectionsystem. In the usual case, the zero speed system unlatches the guardclosure lock once the motion ceases. The third novel invention willrequire that the guard closure locks do not unlatch and only permissionto unlatch is granted by the zero speed system when it indicates thatmotion is terminated. Guard closure locks will then unlatch only ifinterference devices are fully inserted or deployed and if theassociated protective status is communicated to the machine controller.

In summary, the third mentioned novel invention process operates asfollows: When the zero speed detection system issues a signal that themotion has ceased the signal is to be utilized to command and executethe insertion of a motion interference device as a precursor to theunlatching of any interlocked and locked guard closures protecting thepoint of operation. This insertion will prevent, due to any cause, anymotion to be present or resumed in the danger zone after the guardclosure has been unlatched and opened for access. If, after the zerospeed signal has been issued, the interference device can not beinserted the most likely reason is that at the time of insertion zeromotion was not present as indicated and that the motion hazardcontinues. This serves as a signal not to unlatch the guard closure.

The ultimate guard closure system contains interlocks and interlocktesting systems, zero speed monitors with testing capabilities, guardclosures with guard closure testing systems, locks with lock testingsystems and interference devices with their testing systems. Unlatchingof the guard closure usually requires the essentially simultaneouslyfulfillment of the following necessary conditions, 1) tests on guardclosure locks have been passed, 2) tests on guard closures by forcedisplacement devices have been passed, 3) tests on interlocks have beenpassed, 4) tester probe tests have been passed, 5) tests on zero speedindicators have been passed, 6) tests on timer or delay devices havebeen passed, 7) tests on interference systems have been passed, 8)machine power has been interrupted by control stop signals, emergencystop devices or by power disconnect, 9) zero speed systems givepermission to unlatch and, 10) interference devices are fully deployed.

In order to better understand applicant's invention there will beschematically illustrated and described systems employing motiondetectors for indicating when the machine components have completedtheir run down and systems for testing the zero speed indicators withoutshutting the machine down. This may or may not include isolating themotion detector from the machine during testing depending on the systememployed. In addition, an apparatus will be described wherein aninterference device is inserted to prevent accidental resumption ofmotion after all motion has ceased when zero speed is indicated.

In order to better understand applicant's invention there will also bedescribed in detail hereinafter flow charts illustrating an example of amain routine for the testing of safeguarding devices and systems forguard closures as well as a number of subroutines. The subroutinesinclude 1) a zero speed indicator test subroutine for in situ testingwhile the machine is running; 2) a zero speed indicator test subroutinefor in situ testing during the speed run down phases caused by machinestop initiations; 3) a subroutine in which there is insertion of amotion interference device at the completion of the speed run downbrought about by initiating stopping of the machine and 4) a subroutinefor checking the fulfillment of the necessary conditions for unlatchinga guard closure.

BRIEF DESCRIPTION OF DRAWINGS AND FLOW DIAGRAMS

The following drawings and flow diagrams show the applications, methods,concepts, processes and execution of the present novel inventions.

FIG. 1 is a schematic view of a machine control arrangement including asafety control arrangement and a zero speed indicator testing system;

FIG. 2A shows a zero speed indicator assembly connected to the drivingmechanism of a press, where the indicator assembly is to be tested insitu during running of the machine without its shutdown, by temporarilydetaching the indicator assembly in situ from the driving mechanism;

FIG. 2B shows the zero speed indicator assembly of FIG. 2A temporarilydetached in situ from the press driving mechanism, in which position theindicator assembly can be tested while the machine can continue tooperate;

FIG. 3 shows a zero speed indicator connected by a clutch/brake timingbelt unit to the driving shaft of a continuously running circular sawsystem, wherein by temporarily declutching the indicator timing beltdrive shaft from the saw drive shaft and applying the brake to thetiming belt drive shaft the indicator can be tested in situ duringrunning of the saw without its shutdown;

FIGS. 4A and 4B illustrate a flow diagram of a subroutine for in situtesting zero speed indicators while the machine is running;

FIG. 5 shows a zero speed indicator connected to the driving mechanismof a press, requiring intermittent type of operations wherein theindicator without uncoupling can be tested in situ each time the ramcrank shaft is braked to a stop required by an intermittent task of thepress operation, as well as during scheduled and unscheduled stopinitiations of the press power drive itself;

FIGS. 6A and 6B illustrate a flow diagram of a subroutine for in situtesting zero speed indicators during the speed run down phases caused bymachine stop initiations;

FIG. 7 shows the system of FIG. 5 equipped with a separate clutch/brakeunit for the zero speed indicator, whereby it illustrates that combiningmethods and systems of this invention enables the testing of zero speedindicators in situ both while the machine is running and during machinestop initiations using a single test system;

FIG. 8 discloses a system wherein when the guarded machine members reachzero speed a motion interference device is inserted to insure that it isabsolutely safe to open the guard closure;

FIG. 9 is a flow diagram of a subroutine for insertion of a motioninterference device at speed rundown completion caused by machine stopinitiations;

FIG. 10 is a flow diagram of a subroutine for checking the fulfillmentof necessary conditions for unlatching a guard;

FIGS. 11A-1, 11A-2, 11B-1 and 11B-2 are an example of a main routine fortesting safeguarding devices and systems for guard closures thatutilizes the subroutines of FIGS. 4A and 4B, 6A and 6B, 9 and 10.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The novel inventions disclosed herein relate to safety guard systemsthat employ zero speed indicators that are utilized to indicate when thespeed of the machine components they are guarding have come to the stoprequired for the safe access to the guarded space, thereby eitherpermitting or actually effecting the unlocking of the guard closurespreventing access to such machine components. The novel invention alsorelates to the interaction of the zero speed indicator signal with theinsertion of a motion interference device if such a device is part ofthe safety guard system.

The novel inventions provide general methodologies and processes fortesting zero speed indicators by taking advantage of the physical factthat every moving machine element has a “speed rundown phase” when it isrequired to stop for whatever reason. Each rundown phase, whether it isforced to occur for test purposes as described herein, or occurs due tonormal machine operations as also described herein, provides theopportunity to test the zero speed indicator attached to such an elementfor accuracy and reliability, giving in turn the opportunity to make thecorrect decision regarding the unlocking of the safety guards.

The various novel inventions disclosed herein were described in detailin the SUMMARY OF THE INVENTION section. Since these novel inventionsrepresent general methodologies and processes applicable to machinesystems with zero speed indicators, their mechanical embodiments areillustrated here by way of examples only, using schematic depictions ofmachine systems with zero speed indicators and testing arrangements.These are shown in FIGS. 2, 3, 5 and 7. The corresponding processes,executing the testing and decision making for such test arrangements,are illustrated by means of general testing process and decision makingflow diagrams shown in FIGS. 4A and 4B, 6A and 6B, 9, 10, 11A-1 and11A-2, 11B-1 and 11B-2. Finally, FIG. 1 depicts a schematic view of amachine control arrangement including a safety guard control setup and azero speed indicator testing system, applicable to machine systems suchas those illustrated by FIGS. 2, 3, 5, and 7 which would utilize thetest process and decision flows of FIGS. 4A and 4B, 6A and 6B, 9, 10,11A-1 and 11A-2, 11B-1 and 11B-2.

Thus, FIG. 1 shows schematically a machine control and testing system 10which preferably includes one or more machines 11 (one being shown), acontrol unit 12, an input device 13, and an output device 14. The system10 shall also include one or more detection units 15 (one being shown)including for example flow sensors, proximity sensors, heat detectingdevices etc. to detect certain operating conditions of the system.Specifically, the detection unit 15 will include any of a variety ofknown suitable devices for sensing and indicating the functioning and/ormalfunctioning of the various components of the guard closures system.The instant application is directed to the zero speed indicator aspectof the guard closures system which indicators 16 determine if the speedof machine components 17, the access to which is controlled by guards18, has achieved zero speed for the purpose of granting access to theguarded space. The detection unit 15 of the system 10 may communicatewith the control unit 12 by transmission line 19 or any other suitablecommunication link. It will be recognized that the control unit 12, theinput device 13, and output device 14 may be integral with the machine11 or remote from the machine 11.

The guarding systems for the machine components 17 may also include aninterlock such as 20A, 20B etc. for protecting each guard. Alsoillustrated are various locking mechanisms L that can be employed suchas an integral locking mechanism or a separate locking device Sschematically shown with respect to each guard. The various mechanismsare connected to the control unit by transmission lines 21A, 21B etc.The transmission lines may be one way or bi-directional communicationlinks of any suitable type. The interaction between the guards,interlocks and locking devices are described in detail in theaforementioned applications Ser. No. 08/861,328 and 09/033,322 referredto herein and incorporated herein by reference. Thus the schematictesting system of FIG. 1 is not intended to limit the application ofapplicants invention but is merely intended to provide a generaloverview of systems that can be employed.

The control unit 12 can be set to test the guards and/or interlocksand/or zero speed detectors on any specified schedule, for instance,during each shift, hourly, daily, weekly, or any other interval. Signalor warning indicators, can be placed wherever desired, for instance,adjacent to each guard, operating stations and main panels and besuitably activated in the event a guard and/or interlock and/or zerospeed detector fails, to warn personnel of this condition.

In FIG. 1, the input device 13 of the system 10 is in communication withor coupled to the control unit 12. The input device 13 may include akeyboard, a keypad, or any other suitable input device. The input device13 may allow a number of versatile control or scanning functions to beutilized. For example, the guards, interlocks and zero speed indicatorsmay be continuously monitored or checked at preselected times.Alternatively, the frequency and duration of monitoring of all or aselected number of guards, interlocks and zero speed indicators may beinitially preset and/or changed.

The output device 14 of the system 10 is also in communication with orcoupled to the control unit 12. The output device 14 may generate amessage or an alarm that can be visual, audio, or whatever else issuitable, singly or in combination, when a malfunctioning guard systemprotective component, e.g., the interlock or zero speed indicator isdetected. The output device 14 may include a display or monitoring panelthat alerts an operator that a trouble or an alarm condition exists andmay also indicate the location of the malfunctioning device in theenvironment.

The output device 14 may further display a message or otherwise identifywhat is being tested and where, what is bypassed for testing and what isnot (see patent application Ser. No. 08/861,320 and 09/033,322) etc. andthe corrective actions acquired. The output device 14 may be designed atany level of sophistication or complexity in order to process theinformation about the status of the guards, interlocks, zero speedindicators, etc. and to indicate that a problem exists with one or moreof said devices.

The control unit 12 of the system 10 checks where feasible and directsthe functioning and operation of all guards, interlocks, guard locks,zero speed indicators and interference devices as well as other machinecontrols. To execute these tasks the control unit 12 may include, forexample, a program unit, a processing unit, a computer, a programmablelogic controller, a microprocessor, etc. The control unit 12 can becommanded with any suitable operating system, and can be digital,analog, hardwired, etc., or combinations of these. The control unit 12can be commanded to continuously monitor components of the guards'protective system and test the individual protective devices, such asthe zero speed indicators in any sequence combination, at a preselectedschedule, frequency, duration, or randomly.

As indicated previously, when the control unit 12 detects amalfunctioning guard protective component, e.g., an interlock or zerospeed indicator, suitable alarms would be activated at the output device14 and/or at other selected locations, and the control unit 12 may placethe malfunctioning device in a maintenance standby mode as furtherdescribed below. A message indicating a malfunctioning device may alsobe displayed on the output device 14 and elsewhere. The particularlocation of the guard, with the failed protective component of themachine 11 may further be identified.

For the purpose of the present invention the novel systems are directedto the testing of zero speed indicators that are used to indicate whenthe moving machine components being guarded are at zero speed so theguards can be opened without there being a hazard to personnel enteringthe guarded area. This testing would be directed by the control unit 12.

In particular the zero speed indicators 16 are connected via thetransmission lines to the control unit 12 and detection unit 15, toactivate indicators when the components 17 are at zero speed and theguards 18 can be unlocked to be opened. Per the present novel inventionthe control unit 12 is also programmed to periodically test the zerospeed indicators, when the machine is running by uncoupling them fromthe moving machine components and allowing them to run down (FIGS. 2A,2B and FIG. 3), or by testing the zero speed indicators when the machinecomponents being guarded are in the run down phase of a stopping actionof the components of the machine such as described by example withrespect to FIG. 5 hereinafter in detail. If during the testing the zerospeed indicator fails the test, the control unit can be programmed to avariety of ways including 1) to shut down the machine or 2) allow themachine to continue running while insuring that the relevant guardremains locked to continue to guard the machine components monitored bythe faulty zero speed indicator.

In addition the controller 12 can be programmed to further provide forinserting an interference device when zero speed has been achieved (FIG.8) to block the components being guarded from moving while the guard isopen.

FIGS. 2A and 2B illustrate schematically a mechanical embodiment of azero speed indicator assembly connected to the driving mechanism of amachine, shown here as a press, where the indicator assembly is to betested in situ during running of the machine without its shutdown. Themethod illustrated here to accomplish the testing while the machine isrunning is that of temporarily detaching the indicator assembly in situfrom the driving mechanism, in which uncoupled mode the indicatorassembly can be tested while the machine can continue to operate.

Specifically, FIGS. 2A and 2B disclose a schematic illustration of amotion detector that is directly connected to a motor driven gear systemthat drives a crankshaft to which is secured a connecting rod and apress ram. Thus the motion of the detector is directly synchronized withthe motion of the ram, which is the dangerous element of the press. Asshown, the motor 24 drives the crankshaft 25 to which is secured aconnecting rod 26 and ram 27 that is positioned to engage the die 28through the action of the gear train 29. Located adjacent to the drivegear 30 of the gear train 29 is the motion detector assembly 32 thatincludes a detector 32′ and gearing 31 that is normally engaged with anddriven by the main gear 30. The motion detector 32′ through gearing 31is thus driven at a speed that is proportional to that of the crankshaft25, and when the gearing 31 runs down to zero speed due to a machinestop action, the detector 32′ will indicate that the crankshaft 25 hasrun down to zero speed.

The detector assembly 32 is equipped with an uncoupling/couplingmechanism 33 capable to detach the detector gear 31, and thus thedetector assembly 32, from the drive gear 30 and to reattach it to thegear, while the gear 30 is running. When it is desired to test themotion detector 32′ while the machine is running, the motion detectorassembly 32 is temporarily detached in situ by the mechanism 33 from thedrive train gear 30 as shown in FIG. 2B. In this isolated state themotion detector assembly 32 is allowed to freely run down to zero speed,or can be helped to run down to zero speed by a brake. It is monitoredduring this interval by a test device, means or method shownschematically at 34, which can be any suitable verification device ormethod including that recommended by the detector manufacturer, toestablish if the detector 32′ correctly determines and indicates zerospeed. At the completion of the test, the motion detector assembly 32with its gearing 31 is recoupled to the drive train gear 30 by means ofthe mechanism 33 to continue monitoring the ram motion.

It is to be noted that the motion detector can be separate from the rundown component and be stationery but equipped to read the speed of therun down component even when the component is disengaged from themachine for the purpose of testing the detector while the machine isrunning.

The test execution process for the mechanical embodiment of FIGS. 2A and2B and the decisions on the test outcomes are all illustrated in detailin the flow chart diagram of FIG. 4.

FIG. 3 is another illustration of a mechanical system embodiment fortesting a zero speed indicator in situ while the machine is running butusing a clutch/brake unit as the uncoupling mechanism to perform theindicator testing. Here, the machine is illustrated by a circular sawsystem.

Specifically, the embodiment of FIG. 3 shows schematically acontinuously running saw 36 mounted on a power driven arbor shaft 38.Attached to the arbor shaft 38 is a clutch/brake unit 40 which operatesa zero speed detector 42 via the drive shaft 44 and the belt drive unit46. In this way the motion of the detector 42 is proportional to and isdirectly synchronized with the motion of the saw 36, which is thedangerous element of the machine. Thus, when the saw 36 runs down tozero speed due to a stop action of its arbor shaft 38, the detector 42will indicate when zero speed has been achieved.

When it is desired to test the zero speed detector 42 while the saw 36is running, the detector is temporarily uncoupled from the machine bydeclutching its timing belt drive shaft 44 from the saw driving arbor 38using the clutch/brake unit 40. The brake of the clutch/brake unit 40 isthen applied to the timing belt's shaft 44 to run down its motion to astop to test the zero speed detector 42. During this phase, the detector42 is monitored by a test device, means or method shown schematically as48 to establish if the detector correctly determines and indicates zerospeed. The tester 48 can employ any suitable verification device ormethod, including that recommended by the detector manufacturer. At thecompletion of the test, the detector 42 is recoupled to the saw arborshaft 38 by the clutch/brake unit 40 to continue monitoring the speedstatus of the saw 36.

The test execution process for the mechanical embodiment of FIG. 3 andthe decisions on the test outcomes are all illustrated in detail in theflow chart diagram of FIG. 4.

FIG. 4 described below is a flow diagram subroutine detailing the testexecution process and decisions on test outcomes for testing theintegrity and accuracy of zero speed indicators in mechanical systems ofrunning machines in general, in which the test is performed while themachine is running and without stopping the machine, as is embodied inthe present novel invention. As such, this flow diagram is alsoapplicable to the example mechanical systems presented in FIGS. 2 and 3.

The subroutine of FIGS. 4A and 4B is designated by the number 50 and isstarted by selecting a zero speed indicator to be tested at which timethe test states are reset to start the test at 50A. At 50B the “zerospeed indicator test on” informing devices are activated and at 50Cthere is applied a suitable testing device and/or method to the zerospeed indicator's speed run down component for the purpose of testingthe indicator. At 50D the zero speed indicator's run down component isto be uncoupled from the monitored machine component to initiate itsspeed run down without stopping the machine component or the machine. At50E there will be an indication of whether the zero speed indicator didor did not uncouple. If the indicator did not uncouple, it is a testingfailure and thus the indicator cannot be tested. This will be recordedat 50F. Following this at 50G an informing device indicating that thezero speed indicator did not uncouple and thus the indicator cannot betested will be activated, and at 50H will be given a directive and anindication that the guard served by this zero speed indicator is not tobe unlocked until the faults are corrected and the indicator and allassociated tests have passed in situ. At 50I the necessary repair orreplacement of faulty devices will be scheduled. At 50J a decision ismade to 1) shut down the machine due to the failure or 2) to not shutdown the machine and proceed to test another indicator at 50K. If themachine is to be shut down it will be done so at 50L and at 50M the“zero speed indicator test on” informing devices will be deactivated.

Returning now to 50E it follows that if the zero speed indicator diduncouple then at 50N the zero speed indicator will be monitored by thetesting device or method of 50C to ascertain if the indicator correctlydetermines and indicates zero speed of its the speed run down component.At 50P it will be determined if the assigned monitoring time for theindicator has been exceeded.

The use of an assigned finite monitoring time, somewhat longer than theuncoupled indicator's run down time, is necessary in order to avoid anendless monitoring loop or an excessive test time, both of whichindicate a failure of either the zero speed indicator or the testing.Thus, if at 50P it is determined that the monitoring time has beenexceeded, it is a zero speed indicator or a testing failure and theinforming device 50R will be activated indicating that the monitoringtime has been exceeded (a failure). At 50H the directive and indicationwill be given that the guard served by this zero speed indicator is notto be unlocked until the faults are corrected and the indicator and allassociated tests have passed in situ. This is followed as before by theaction of block 50I, the decision block 50J, and the branch blocks 50Land 50M, or the decision block 50K.

If at 50P it is determined that the assigned monitoring time has not yetbeen exceeded, then at 50Q it will be indicated if zero speed has beenachieved or not as monitored at 50N. If zero speed is not indicated at50Q, then the process loops again through block 50N and branch blocks50P and 50Q. If zero speed is indicated at 50Q, then at 50S it will benoted if the zero speed indicator performed correctly or not.

If the zero speed indicator did not perform correctly 50T will recordthat the indicator failed the test. If the zero speed indicator passedthe test then at 50U it will be so indicated. Whatever the test outcome,the indicator's speed run down component is then to be recoupled to themachine component it is assigned to monitor at 50V. At 50W it will benoted if the zero speed indicator recoupled or not and if it did notrecouple then at 50X a record will be made that the recoupling failedand a test outcome decision will be made at 50AA. If the indicator didrecouple it will be so recorded at 50Y. At 50Z the testing device ormethod of 50C will be removed from the zero speed indicator's run downcomponent and at 50AA the test outcome decision will be made if alltests have passed. If all tests have passed the “all tests passed”informing devices are activated at 50BB whereupon the process goes todecision block 50K. If all tests did not pass the “test failed” warninginforming devices indicating what tests failed are activated at 50CCafter which the system returns to 50H wherein the guard is not to beunlocked.

FIG. 5 illustrates schematically a mechanical embodiment of a zero speedindicator connected to the driving mechanism of a machine, shown here asa press requiring intermittent stop type of operations, wherein theindicator without uncoupling can be tested in situ each time the ramcrank shaft is braked to a stop required by an intermittent task of thepress, as well as during scheduled and unscheduled stop initiations ofthe press power drive itself.

In FIG. 5, the motor 52 drives the pulley system 53 which in turnrotates the flywheel 54. The flywheel is connected to a clutch and brakeunit 56 through which the crankshaft 57 and associated connecting rod 58is driven to reciprocate the ram 60. In this system is shown a zerospeed indicator 62 that is connected to the crankshaft 57 through thetiming belt 64. The indicator 62 is used to determine when a protectiveguard (not shown) can be unlocked to allow safe operator access to thedangerous space of the ram 60 and die 66 operation.

Any time the machine is declutched and braked to a stop at 56 due to anintermittent operation requirement of the ram 60, there is anopportunity to test in situ the reliability and accuracy of the zerospeed indicator 62 by the schematically illustrated tester 68 during thespeed run down phase of the stop without interruption of production. Thetester 68 can be any suitable verification device or method includingthat recommended by the indicator manufacturer. Furthermore, wheneverthe press is shut down by control stops, emergency stops or powerdisconnects, there is the same opportunity to check or test in situ thereliability and accuracy of the zero speed indicator 62. Unlike thetesting of the zero speed indicators during running of a machine asillustrated in, FIGS. 2, 3 and 4, the present testing, FIG. 5, beingdone during stop initiations requires no special means for uncouplingthe zero speed indicator from its driving machine component.

If the indicator fails the test then the decision can be made not topermit the unlocking of the protective guard until a scheduledrepair/replacement and retest have been performed. These and otherdecisions on the test outcomes as well as the test execution process forthe mechanical embodiment of FIG. 5 are all illustrated in detail in theflow chart diagram of FIG. 6.

FIGS. 6A and 6B described below is a flow diagram subroutine detailingthe test execution process and decisions on test outcomes for testingthe integrity and accuracy of zero speed indicators in mechanicalsystems of running machines in general, in which the test is performedduring machine stop initiations, as is embodied in the present novelinvention. As such, this flow diagram is applicable to the examplemechanical system presented in FIG. 5.

The subroutine of FIG. 6 is designated by the number 70. As isindicated, such a subroutine for testing an individual zero speedindicator can be applied simultaneously to all relevant zero speedindicators of the machine required to be tested by the machine stopinitiation. However, the test outcome results are specific to each zerospeed indicator. The subroutine process starts at 70A where it isindicated that the speed run down of the monitored machine componentshas been initiated by the main routine controller

At the start of the run down phase at 70B it is noted that three thingsoccur in parallel. Specifically, at 70C a zero speed indicator isselected to be tested at which time the test states will be reset to thestart of tests. At 70D the “zero speed indicator test on” informingdevices are activated and at 70E will be applied a suitable testingdevice and/or method to the zero speed indicator's speed run downcomponent for the purpose of testing the indicator. At 70F the indicatorwill be monitored by the testing device or method of 70E to establish ifit correctly determines and indicates zero speed of its speed run downcomponent. At 70G it will be determined if the assigned monitoring timefor the indicator has been exceeded or not.

The use of an assigned finite monitoring time, somewhat longer than theuncoupled indicator's run down time, is necessary in order to avoid anendless monitoring loop or an excessive test time, both of whichindicate a failure of either the zero speed indicator or the testing.Thus, if at 70G it is determined that the monitoring time has beenexceeded, it is a zero speed indicator or a testing failure and theinforming device 70H will be activated indicating that the monitoringtime has been exceeded (a failure).

At 70I it will be directed that the guard closure served by theindicator is not to be unlocked until the faults are corrected and theindicator has passed the test in situ. If the assigned monitoring timeat 70G has not been exceeded 70J determines if zero speed has beenindicated and if not the system returns to 70F where it will againmonitor if the indicator correctly determined the speed. If zero speedis indicated at 70J then the system proceeds to 70K which will indicatewhether or not the indicator performed correctly. If the indicator didnot perform correctly 70L will record that the indicator failed thetest. If the indicator did pass the test this will be recorded at 70M.70N indicates if the test passed or not and if it did not the “testsfailed” warning informing devices are activated at 70P. From 70P thesystem leads to 70I which informs and directs the system that the guardclosures are not to be unlocked. If the indicator passed the test thenthe “test passed” informing devices are activated at 70Q and at 70R theindicator testing device will be removed from the zero speed run downcomponent. At 70S the “zero speed indicator test on” informing devicesare deactivated after which the system returns to its main routine (FIG.11) at 70T.

It has previously been noted that at 70P the test failed warning deviceswere activated. Then via step 70I we get to step 70U where the necessaryreplacement and/or repair would be scheduled and at 70V the indicatortesting device would be removed from the zero speed indicator's run downcomponent. At 70W the decision is made whether restarting of the machinecomponents served by this failed indicator is to be permitted. If thedecision is yes, then it is so communicated to its main routine (FIG.11) at 70T, but if restarting of the machine components is to beprevented then at 70X it is so executed and the “zero speed indicatortest on” informing devices will be deactivated at 70S.

FIG. 7 shows that combining methods and systems of this inventionenables the testing of zero speed indicators in situ both during machinestop initiations and while the machine is running using a single testsystem.

Thus FIG. 7 shows the schematic mechanical system of FIG. 5 with thesame interconnecting arrangement of its parts 52 through 68, as that ofFIG. 5. However, here the timing belt 64 of the zero speed indicator 62is connected to the crankshaft 57 by an intervening clutch/brake unit 70by means of the timing belt drive shaft 74 in the manner shown in FIG. 3(parts 40 and 44 of FIG. 3). With this arrangement, the zero speedindicator 62 of FIG. 7 can be tested in situ during scheduled andunscheduled stop initiations as described for FIG. 5, and it can also betested in situ during running of the machine as described for FIG. 3.The test execution processes and decisions on outcomes would be those ofFIG. 6 and FIG. 4 respectively.

FIG. 8 illustrates a schematic arrangement of a mechanical motioninterference safety device of the type that may be used with plasticinjection molding machines. Specifically, this embodiment incorporates amoving platen 76 to which is connected a safety bar 78 that has formedtherein a number of recesses 80. When the schematically illustratedmotion indicator 82 has signaled that zero speed has been achieved bythe moving platen a motion blocking interference device 84 engages arecess 80 in the safety bar 78 to prevent movement of the platen 76. Inthis embodiment the interference device is a pawl 84 that is controlledby an actuating valve 85. The actuating valve operates in response tothe motion detector 82 reaching zero speed to introduce fluid to thesafety pawl actuating cylinder 86 to move the pawl 84 into a recess 80to lock the movable platen 76 in position. Moving the pawl into lockingengagement with the safety bar 78 is a precursor to allowing theunlatching of any interlocked or locked guard closure such as the gate88 protecting the machine components. Closing the gate 88 after it hasbeen allowed to open, reverses the operation of the pawl 84 allowing themoving platen 76 to operate again.

FIG. 8 is but one example of the use of a mechanical motion interferencesafety device. There are obviously many other machinery systems whichcan, will and do employ mechanical motion interference safety devices ofvarious kinds.

FIG. 9 illustrates a flow diagram subroutine detailing the executionprocess and decisions on process outcomes for insertion of a motioninterference safety device at speed rundown completion caused by machinestop initiations of a general machine. It therefore also applies to theexample system of FIG. 8.

The subroutine of FIG. 9 is referred to by the number 90. At 90A themachine stop signal has been initiated and the relevant machine memberis in the speed run down phase. At 90B using a tested and passed zerospeed indicator the speed of the relevant machine member is monitored.At 90C it will be determined if the indicator signals that the machinemember did or did not achieve zero speed. If it did not achieve it itwill be determined at 90D if the assigned monitoring time has beenexceeded. If the monitoring time has not been exceeded the systemreturns to 90B. If the assigned monitoring time has been exceeded it isa failure then at 90E an informing device will be activated indicatingthat the monitoring time has been exceeded. Then at 90F it is directedthat the guard closure is not to be unlocked until the faults arecorrected. Following this at 90G there will be activated a warninginforming device that the “interference device was not inserted”.Subsequently at 90H the necessary repair or replacement of the faultydevice will be scheduled. At 90I the motion blocking interference deviceis to be restored to its starting position if an attempt to insert itwas made. At 90J will be decided whether to permit the restart of therelevant unblocked but locked guard protected machine components. If thecomponents are to be allowed to restart this is done at 90K by the mainroutine of FIG. 11. If it is decided not to restart the relevant machinecomponents the prevention will be executed at 90L.

Returning to 90C if it has been indicated that zero speed has beenachieved then at 90M an attempt is made to insert the motion blockinginterference device into the assigned machine location. At 90N it willbe determined if the interference device can be inserted and if itcannot be inserted then 90F will signal that the guard closure shouldnot be unlocked until the faults are corrected. If the interferencedevice is inserted then at 90P the “insertion completed” informingdevice is activated and at 90Q permission is granted to unlatch theguard closure for the relevant blocked machine components whereupon thesubroutine 90 returns at 90K to the tasks of the main routine of FIG.11.

Attention is now directed to FIG. 10 which illustrates a flow diagramsubroutine for checking the fulfillment of necessary conditions forunlatching a guard closure. This subroutine is indicated as 92 and at92A the guard closure to be checked is identified. At 92B are selectedthe latest test, monitoring and probing results for the guard closure,its safeguarding devices and systems. Then at 92C it will be determinedif the results satisfy the specified necessary conditions for unlatchingthe guard closures. If they do not then at 92D permission will not begranted to unlatch the guard closure until the faults are corrected. Ifpermission is granted to unlatch the closure this is given at 92E andthe subroutine is returned to its main routine (FIG. 11) at 92F. At 92Dit is noted that permission is not granted to unlatch the guard closureand then at 92G there will be an indication that the necessaryconditions are not satisfied and the “failed condition” informingdevices will be activated. At 92H repair or replacement of the faultydevices will be scheduled after which there is a return at 92F to thesubroutines main routine of FIG. 11.

It is to be noted that for the ultimate guard closure system thenecessary conditions for unlatching the guard closure must include thefollowing results: a) tests of the guard closure locks have been passed;b) tests on guard closures by force/displacement devices have beenpassed; c) tests on interlocks have been passed; d) tests on zero speedindicators have been passed; e) zero speed systems gives permission tounlatch the closure locks; f) tests on timers or delay devices have beenpassed; g) tests on interference systems have been passed; h)interference devices are fully deployed; i) test of testers have beenpassed and; j) machine power has been interrupted by control stopsignals, emergency stop devices, or by power disconnects. Insofar as thedetails for accomplishing a), b) and c) are concerned reference is againmade to the two applications 08/861,328 and 09/033,332, relating to suchtesting systems previously referred to.

We now turn to FIGS. 11A-1, 11A-2, and 11B-1, 11B-2 where there is anexample of a main routine for testing safeguarding devices and systemsfor guard closures which directs and executes the use of the process anddecision subroutines, FIGS. 4A and 4B, 6A and 6B, 9 and 10 previouslydescribed. This system is designated as 94 and begins with the machinesystem control unit at 94A. At 94B it will be determined if the maindisconnect which is to be closed or opened at 94C has been closed. Ifthe main disconnect has not been closed the machine is stopped at 94Dand at 94E after the machine motion has stopped the guards will beunlocked if required and permitted. Following this the routine will beended at 94F. If the main disconnect is closed then 94G will indicate ifthe control is or is not in the start position if preceding this thestart/stop control has been activated at 94H. If the control is not inthe start position then as indicated at 94I the machine is stopped andthe system returns to 94F. If the control is in the start position at94G then the emergency stop controls are checked if they are activatedat 94J. Here again, emergency or other stop controls are activated ordeactivated at 94K. If the stop controls are activated the machine willbe stopped at 94L. After the machine motion has stopped the guards willbe unlocked if required and permitted at 94M.

If the stop controls are not activated then 94N will indicate whetherinput/output controls are enabled. If the input/output controls are notenabled then 94P will enable the machine input/output controls. If theyare enabled then at 94Q it will be indicated if the machine controlsother then for interlocks/locks are satisfied. If they are not satisfiedthen the machine will be stopped at 94S. If the machine controls aresatisfied at 94Q the state of the interlock/locks sensors determinationis done at 94T. If the sensors states are satisfied then at 94V it isdetermined if the interlock/lock bypass was enabled by its testsubroutine. If the interlock/lock bypass is not enabled the machine willbe stopped at 94S. If the interlock/lock bypass is enabled then at 94Wit will be ascertained if the interlock/locks and or guard closuretesting is in progress. If the testing is in progress the system returnsto the machine system control unit at 94A. If the interlock/locks and/orguard closure testing is not in progress it will be determined if themachine is running at 94X. If the machine is running 94Y 11B-1 willdetermine whether to initiate a machine component stop or not, orwhether the machine is to be shut down or not. If the component is to bestopped or the machine is to be shut down then at 94Z 11B-1 it will bedecided whether to initiate and conduct tests of safeguarding devicesand safeguarding systems for guard closures and/or for insertion ofmotion interference devices as a precursor to the stop/shut down. If itis not desired to initiate and conduct tests then the system returns tothe control unit at 94AA. However, if tests are to be conducted then thecorresponding test subroutines are selected at 94BB for the guardclosures to be tested and/or have motion interference devices inserted.The machine rundown phase will then be initiated at 94CC.

Following 94CC various choices are available and made which in parallelwith returning to the control unit at 94DD and then back to the machinesystem control unit at 94A. They are; 1) select and conduct a zero speedindicator test per test subroutine of FIG. 6 at 94EE or 2) at 94FFselect and conduct interlock/lock and/or guard closure tests per therequired test subroutines that are discussed in detail in theaforementioned patent application Ser. Nos. 08/861,328 and 09/033,322that were incorporated herein reference; or 3) at 94GG select andperform a motion interference device insertion per the subroutine inFIG. 9. Following one of items 1, 2, or 3 hereinabove the machinecomponent or machine is stopped at 94HH and subsequently at 94II aselection is made to open or not open one or more guard closures. If thechoice is not to open a guard closure the system returns to 94JJ whereit is determined whether the machine restart is prevented by thedecision process of the subroutine that detected a fault. If isdetermined to open one or more guard closures the guard closure to beopened, is selected at 94KK and for each guard closure to be opened itis checked at 94LL by means of the subroutine of FIG. 10 if permissionis granted to open the guard closure. Where permission has been grantedthe designated guard closures will be unlocked and opened at 94MM. At94NN, action will be taken to assure that those guard closures for whichpermission to open has not been granted will remain closed and lockeduntil necessary repairs or replacements have been made after which thesystem returns to 94JJ.

Returning to 94Y if a component stop or machine shut down is not madethere will be a determination as to whether there will be an initiationand conducting of tests of safeguarding devices and safeguarding systemsfor guard closures at 94PP. If the decision is made not to conduct suchtests there will be a return to the control unit at 94QQ. If tests areto be conducted a guard closure to be tested is selected along with thecorresponding test subroutines at 94RR. Following this there are inparallel with returning to the control unit at 94TT two choicesavailable; 1) conduct interlock/lock and/or guard closure test perrequired test subroutine at 94SS or 2) conduct zero speed indicatortests per test subroutine of FIG. 4 at 94UU. At 94VV there will be adetermination if the machine has been shut down by any subroutine due tofault detection. If it has been shut down the machine will be stopped at94WW or if not the system will be returned to the control unit at 94XX.If the machine is stopped the necessary repair and/or replacementelements to enable restart of the machine will take place at 94YYfollowing which the system returns to 94F 11A-2, which completes thetasks of the main routine 94.

It remains to note that if the machine is not running at 94X then theguard closures will be closed and locked for machine start-up at 94ZZand it will be determined at 95 whether or not the machine is to bestarted. If at 95 the machine is to be started, then at 95A it ischecked if the machine is running or not. If not running, the systemreturns to 94S which completes the tasks of the main routine 94. If at95A the answer is yes the machine is running, then the system goes to94Y 11B-2. If at 95 it is decided not to start the machine then thesystem goes to 94S, the end of the tasks of the main routine.

It is intended to cover by the appended claims all such embodiments thatcome within the true spirit and scope of the invention.

1-8. (canceled)
 9. The method of testing whether a machine is at zerospeed initially by a speed indicator to permit opening of a locked guardclosure and subsequently insuring the accuracy of the speed indicator bythe insertion of an interference device comprising the steps ofattempting to insert an interference device into a receiving portion ofa machine component after the speed indicator has indicated zero speedand communicating the status of the interference device to a machinecontroller whereby if the interference device is fully inserted, thelocked guard closure will be given permission to unlatch but if theinterference device cannot be fully inserted or deployed, the lockedguard closure will remain locked. 10-13. (canceled)
 14. Apparatus fortesting whether a machine is at zero speed and insuring that the movingcomponents of a machine has come to a complete stop during run downbefore a closure guarding the moving components can be opened includinga locked closure for the moving component, a zero speed indicator forrecording the speed of the moving components, and sensing when thecomponent has come to a complete stop, an interference device disposedadjacent to the moving component and inserting the interference deviceto prevent further movement of the moving components when the movingcomponent has reached zero speed and opening of the closure guarding themoving component. 15-28. (canceled)